U.S. patent application number 11/189005 was filed with the patent office on 2006-01-05 for systems and methods for automated telescope alignment and orientation.
Invention is credited to Kenneth W. Baun, John E. Hoot.
Application Number | 20060001956 11/189005 |
Document ID | / |
Family ID | 29218358 |
Filed Date | 2006-01-05 |
United States Patent
Application |
20060001956 |
Kind Code |
A1 |
Baun; Kenneth W. ; et
al. |
January 5, 2006 |
Systems and methods for automated telescope alignment and
orientation
Abstract
Embodiments of an automated telescope system are operable in
multiple modes, including alt-az and equatorial modes. The
telescope system aligns and orients itself to the celestial
coordinate system using, for example, data gained through tracking
the drift of a celestial object. In various embodiments, an imager
may be used to find and track celestial objects.
Inventors: |
Baun; Kenneth W.; (Trabuco
Canyon, CA) ; Hoot; John E.; (San Clemente,
CA) |
Correspondence
Address: |
KNOBBE MARTENS OLSON & BEAR LLP
2040 MAIN STREET
FOURTEENTH FLOOR
IRVINE
CA
92614
US
|
Family ID: |
29218358 |
Appl. No.: |
11/189005 |
Filed: |
July 25, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09771385 |
Jan 26, 2001 |
6922283 |
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11189005 |
Jul 25, 2005 |
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09428866 |
Oct 26, 1999 |
6392799 |
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09771385 |
Jan 26, 2001 |
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60105626 |
Oct 26, 1998 |
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60143637 |
Jul 14, 1999 |
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60178840 |
Jan 26, 2000 |
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Current U.S.
Class: |
359/430 ;
359/399 |
Current CPC
Class: |
G02B 23/00 20130101;
Y10S 359/90 20130101; G02B 23/16 20130101; G02B 23/06 20130101 |
Class at
Publication: |
359/430 ;
359/399 |
International
Class: |
G02B 23/00 20060101
G02B023/00 |
Claims
1. A method of aligning an optical system by tracking a celestial
object's drift, the method comprising: monitoring movement of a
celestial object; and electronically determining a relationship
between an observation system and a celestial coordinate system
based on a direction of the movement and a magnitude of the
movement of the celestial object.
2. The method of claim 1, wherein the monitoring further comprises
electronically deriving movement vectors.
3. The method of claim 2, wherein the deriving movement vectors
further comprises electronically identifying the direction and the
magnitude of the movement.
4. The method of claim 3, wherein the identifying further comprises
manually following the movement of the celestial object with a
telescope system.
5. The method of claim 1, wherein the determining a relationship
further comprises electronically determining an orientation of the
observation system with respect to the celestial coordinate system
when the celestial object is a known celestial object in the
celestial coordinate system.
6. The method of claim 5, wherein determining the orientation
includes electronically determining local sidereal time.
7. An alignment system capable of generating instructions to
position at least optical components of an instrument usable to
view distant objects and capable of aligning the optical components
with celestial objects, The alignment system comprising: software
instructions stored in a computer readable medium and capable of
instructing a microprocessor to determine latitude of at least
optical components of an instrument usable to view distant objects;
and software instructions stored in the computer readable medium
and capable of instructing the microprocessor to determine
longitude of the optical components by evaluating a track of a
known celestial object through the sky.
8. The alignment system of claim 7, wherein the software
instructions capable of instructing the microprocessor to determine
latitude include software instructions capable of causing the
optical components to point toward a pole star and then to point
toward the horizon.
9. The alignment system of claim 7, wherein the software
instructions capable of instructing the microprocessor to determine
latitude include software instructions for approximating the
latitude.
10. The alignment system of claim 9, wherein the approximation is
about 38.degree. N.
11. The alignment system of claim 9, wherein the approximation uses
iterative corrections.
12. The alignment system of claim 11, wherein the iterative
corrections comprise repositionings of the optical components in
order to track the known celestial object.
13. The alignment system of claim 12, wherein the repositionings
comprise manual repositionings.
14. The alignment system of claim 7, wherein the software
instructions capable of instructing the microprocessor to use
altitude data at a plurality of viewing positions of the known
celestial object as it tracks through the sky.
15. The alignment system of claim 7, wherein the software
instructions capable of instructing the microprocessor to use data
sensed from one or more of a tilt sensor, a North sensor, a South
sensor, an MR sensor, global positioning system (GPS), a
differential GPS, and a NMEA interface.
16. A method of precisely aligning a telescope system, the method
comprising: determining a level position and a pole (N/S) position
of a telescope system; electronically slewing to an area of a known
celestial object; centering a field of view on the known celestial
object; tracking the known celestial object as it moves through the
sky; and electronically determining an orientation of the telescope
system with respect to a celestial system.
17. An electronically positioned telescope system including a
telescope and one or more microprocessors capable of instructing
motor systems to position the telescope, the telescope system
comprising: a first motor system capable of rotating a telescope
about one of two orthogonal axes; a second motor system capable of
rotating the telescope about the other of the two orthogonal axes;
and a microprocessor capable of providing instructions to and
receiving position information from the first and second motor
systems, wherein the microprocessor is configured to instruct the
first and second motor systems to slew the telescope to a celestial
object, to acquire position information corresponding to movements
of the first and second motor systems as the telescope tracks a
celestial object over time, and to determine a relationship between
a celestial coordinate system and the telescope from at least
portions of the position data.
18. The electronically positioned telescope system of claim 17,
wherein the celestial object is an arbitrary celestial object.
19. The electronically positioned telescope system of claim 17,
wherein the microprocessor is configured to instruct the first and
second motor systems to slew the telescope to a celestial pole, to
resolve an orientation of a pole star cluster using an electronic
imager, and to determine a precise orientation of the telescope
with respect to a celestial system.
20. The electronically positioned telescope system of claim 17,
wherein the microprocessor is also capable of providing
instructions to the first and second motor systems that cause the
telescope to automatically track a drift of a known celestial
object over time.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority benefit under 35
U.S.C. .sctn. 120 to, and is a continuation of U.S. patent
application Ser. No. 09/771,385, filed Jan. 26, 2001, entitled
"Systems and Methods for Automated Telescope Alignment and
Orientation," (the "Parent Application"), which is a
continuation-in-part of U.S. patent application Ser. No.
09/428,866, filed Oct. 26, 1999, entitled "Fully Automated
Telescope System with Distributed Intelligence," now U.S. Pat. No.
6,392,799, which claims priority benefit under 35 U.S.C. .sctn.
119(e) from U.S. Provisional Application Nos. 60/105,626, filed
Oct. 26, 1998 entitled "Fully Automated Telescope System With
Distributed Intelligence," and 60/143,637, filed Jul. 14, 1999,
entitled "Self Orienting, Self Aligning, Intuitive Automated
Telescope." The Parent Application also claims priority benefit
under 35 U.S.C. .sctn. 119(e) from U.S. Provisional Application No.
60/178,840, filed Jan. 26, 2000, entitled "Systems and Methods for
Automated Telescope Alignment and Orientation." The present
application also incorporates each of the foregoing application
herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to automated telescope systems
and, more particularly, to systems and methods for aligning and
orienting such automated telescope systems.
[0004] 2. Description of the Related Art
[0005] The continuing evolution of low cost, high performance
integrated circuit processors has enabled the recent introduction
of fully automated telescope systems which are capable of
performing alignment and orientation operations under software
program control with a minimum of intervention by a user. Telescope
systems are able to perform alignment and orientation functions
regardless of whether they might be configured as an alt-azimuth
telescope or as an equatorial telescope. The system is provided
with sufficient processing power and with a multiplicity of
application routines, such that alignment and orientation is
performed with regard to a large number of different algorithms and
with respect to a variety of user definable data-type inputs.
[0006] Such telescope systems might be described as intelligent, in
that they typically include a command module which is a fully
functional microprocessor controlled command unit, capable of
executing high level application software routines and performing
numerous data processing tasks, such as numerical calculations,
coordinate system transformations, database manipulations, and
managing the functional performance of various different
peripherally coupled devices.
[0007] Central interface panels might be provided on the telescope
systems which support interconnection between and among various
intelligent motor modules, command modules and peripheral devices.
Communication between and among component parts is made over serial
data and control communication channels in accordance with a
packet-based serial communication protocol. An RS-232 port is also
provided such that a command module is able to communicate with
ancillary RS-232 capable devices such as personal computer
systems.
[0008] Use of the various communication channels allows the
telescope system to communicate with other devices in order to
exchange stored information, exchange created and stored operating
routines, obtain updates to programs and/or internal databases, and
the like. In this regard, such computer systems include a number of
internal databases, including at least one database of the
celestial coordinates (RA and DEC) of known celestial objects that
might be of interest to an observer. Further, the system might
include a database of the geographical coordinates (latitude and
longitude) of a large body of geographical landmarks. These
landmarks might include known coordinates of cities and towns,
carte graphic features such as mountains, and might also include
the coordinates of any definable point on the earth's surface whose
position is stable and geographically determinable. Each of the
databases are user accessible such that additional entries of
particular interest to a user might be included.
[0009] Distributed intelligence might be further characterized in
that the telescope system hand-held command module might be
provided in two separate configurations. The first configuration
might be termed a simplified configuration, and might be
functionally limited in that it is able to provide direction and
speed commands to the intelligent motor modules, but might only be
provided with limited operational command processing capabilities
so as to offer a low-cost alternative. In this particular
configuration, system intelligence would reside primarily in the
motor modules, with the command module functioning more as a
steering guidance control, or directional joystick. However, even
given its reduced computational elegance, the simplified command
module is nevertheless capable of executing a wide variety of
command instructions including those relating to numerical
processing and arithmetic calculations.
[0010] In particular, the solution to any given problem in
celestial trigonometry depends on being able to convert
measurements obtained in one coordinate system (Alt-Az, for
example) into a second coordinate system (the celestial coordinate
system). Performing such coordinate system transformations is well
within the capability of limited functionality processors such as
might be provided with a limited intelligence command module.
[0011] Accordingly, limited intelligence command modules should be
able to support various alignment and orientation schemes so as to
allow a simplified automated telescope system the ability to align
and orient it self with respect to the celestial sphere and provide
a relatively unsophisticated user with capability of, at least,
tracking a designated viewing object throughout its determinable
motion across the night sky.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] These and other features, aspects and advantages of the
present invention will be more fully understood when considered
with respect to the following detailed description and accompanying
drawings wherein:
[0013] FIG. 1 is a semi-schematic perspective view of one
embodiment of a reflecting-type telescope system in accordance with
the present invention;
[0014] FIG. 2 is a semi-schematic perspective view of a second
embodiment of a refracting-type telescope system in accordance with
the invention;
[0015] FIG. 3a is a semi-schematic block diagram of the signal and
bus configuration an the electrical interface panel of the
telescope system of FIG. 2;
[0016] FIG. 3b is a semi-schematic partial perspective view of an
electrical interface panel of the telescope system of FIG. 2;
[0017] FIG. 4 is a semi-schematic front view of an embodiment of a
semi-intelligent dual-axis drive motor motion control system
according to practice of principles of the present invention;
[0018] FIG. 5 is a semi-schematic block diagram of the electronic
components of the embodiment of the semi-intelligent dual-axis
drive motor motion control system of FIG. 4;
[0019] FIG. 6 is a semi-schematic front view of an intelligent
dual-axis drive motor motion control system according to practice
of principles of the present invention;
[0020] FIG. 7 is a semi-schematic block diagram of the electronic
components of the embodiment of the intelligent dual-axis drive
motor motion control system of FIG. 6;
[0021] FIG. 8 is a conceptual flow diagram of an initialization
procedure in accordance with the invention;
[0022] FIG. 9 is a database table illustrating an exemplary
location entry;
[0023] FIG. 10 is a conceptual flow diagram of a first, "easy"
Alt-Az alignment and orientation procedure in accord with the
invention;
[0024] FIG. 11 is a conceptual flow diagram of a second, single
star, Alt-Az alignment and orientation procedure in accord with the
invention;
[0025] FIG. 12 is a conceptual flow diagram of a first alignment
and tracking procedure in accord with the invention;
[0026] FIG. 13 is a conceptual flow diagram of a second alignment
and tracking procedure in accord with the invention;
[0027] FIG. 14 is a semi-schematic illustration of the proper
motion of a celestial object moving in accordance with a sidereal
rate;
[0028] FIG. 15 is a semi-schematic illustration of a curvilinear
travel path of an object illustrating changes in altitude and
azimuth.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0029] The detailed descriptions of an automated telescope system
with distributed intelligence and alignment, orientation and
tracking ability, set forth below in connection with the appended
drawings are intended only as a description of the presently
preferred and illustrated embodiments of the invention, and are not
intended to represent the only form in which the present invention
may be constructed or utilized. The detailed descriptions set forth
the construction and function of the invention, as well as the
sequence of steps utilized in its operation, in conjunction with
the illustrated embodiments. It is to be understood by those having
skill in the art, that the same or equivalent functionality may be
accomplished by various modifications to the exemplary embodiments
without departing from the spirit and scope of the invention.
[0030] An automated telescope system, with distributed intelligence
and a control system for operating such a telescope, will now be
described with reference to the embodiments illustrated in the
figures. In FIG. 1, a telescope system 10 for observing celestial
and terrestrial objects is provided in accordance with the present
invention. Telescope system 10 suitably comprises a telescope tube
12 which houses the optical system required for resolving distant
objects and further includes a focusing objective and eyepiece 14
coupled to the optical system in a manner to allow the observation
of the optical system's focal plane. The telescope tube 12 is
supported by a mount 16 which facilitates movement to the telescope
tube 12 about two orthogonal axes, a substantially vertical axis,
termed an azimuth axis and a substantially horizontal axis, termed
an altitude axis. As those having skill in the art will appreciate,
the horizontal and vertical axes of the mount 16 in combination,
define a gimbaled support for the telescope tube 12 enabling it to
pivot in a horizontal plane defined by the vertical (or azimuth)
axis and, independently, to pivot through a vertical plane defined
by the horizontal (altitude) axis.
[0031] It should be noted, at this point, that telescope system 10
is illustrated as comprising a telescope tube 12 configured as a
reflecting-type telescope, particularly a Maksutov-Cassegrain
telescope. In this regard, the form of the telescope's optical
system, per se is not particularly relevant to practice of
principles of the present invention. Thus, even though depicted as
a reflector, the telescope system 10 of the present invention is
eminently suitable for use with refractor-type telescope optical
systems. The specific optical systems used might be Newtonian,
Schmidt-Cassegrain, Maksutov-Cassegrain, or any other conventional
reflecting or refracting optical system configured for telescopic
use.
[0032] In the telescope system embodied in FIG. 1, it is convenient
to support the telescope tube and mount combination in such a
manner that the vertical axis 18 is, indeed, substantially vertical
such that the telescope pivots (or rotates) about the vertical axis
in the plane which is substantially horizontal. A tripod
conventionally functions to support the mount 16 such that the
azimuth axis 18 is substantially orthogonal to a horizontal plane,
relative to the user of a telescope system. The tripod is
conventionally configured to include three supporting legs, which
are arranged in a triangular pattern. Each of the legs are
independently adjustable for leveling the mount 16 in order to
conform to the nature of the surface upon which the telescope
system 10 is used.
[0033] In addition to supporting telescope motion about two
orthogonal axes, the mount 16 is constructed to include an
electrical interface junction panel 30 which allows various
electronic components comprising the telescope system to be
interconnected and to support interoperability. The electrical
interface junction panel 30 is configured to support upgradeability
of the telescope system 10 to a fully intelligent automatic
telescope system in a series of logically consistent steps, each of
which results in a fully functional telescope system having a
greater or lesser degree of intelligence and/or functionality,
depending upon where, along the upgrade spectrum, a user would
achieve the most subjectively desirable ratio of system complexity
as a function of functional benefit.
[0034] Turning now to FIG. 2, there is depicted a semi-schematic
perspective view of a refracting-type telescope system suitable for
practice of principles of the invention. Since telescopes are
fungible in the context of the invention, like elements such as the
telescope tube 12, mount 16, azimuth axis 18 and altitude axis 20,
will be identified with the same numerals as the corresponding
telescope system of FIG. 1. Additionally, the telescope system of
FIG, 2 includes semi-intelligent motor portions for pivotally
moving the telescope about the azimuth axis 18 and altitude axis
20. Semi-intelligent motor portions suitably comprise a
semi-intelligent, self-contained azimuth axis drive motor 32 and a
semi-intelligent, self-contained altitude axis drive motor 34. Each
of the drive motor assemblies 32 and 34 are self-contained motor
packages including a DC brush-type motor, an associated electronics
package hosted on a printed surface board, a drive and reduction
gear assembly and an optical encoder assembly, configured together
in a housing in a manner according to co-pending patent application
entitled "Intelligent Motor Module For Telescope Axial Rotation,"
Ser. No. 09/428,866, filed on Oct. 26, 1999 and commonly owned by
the assignee of the present invention, the entire of disclosure of
which is expressly incorporated herein by reference.
[0035] The semi-intelligent motor assemblies 32 and 34 are each
affixed to the telescope mount 16 and coupled to the azimuth and
altitude axes, 18 and 20, respectively, so as to be able to
pivotally move the telescope tube 12 about the corresponding axis
when the motor assembly is activated. Each of the motor assemblies
32 and 34 are plugged into respective corresponding receptacles in
the electrical interface junction panel 30 which, in a manner to be
described in greater detail below, functions as a signal interface
for the motor assemblies as well as providing power and ground
thereto.
[0036] The electrical interface junction panel 30 allows motor
control signals to be directed to each of the motor assemblies 32
and 34, the motor control signals providing speed and direction
information to the electronics package which, in turn, provides
appropriate activation signals to the respective DC motor
comprising each motor assembly. The electrical interface junction
panel 30 further allows for signal communication between each
respective one of the motor assemblies 32 and 34 and a hand-held
system control unit 36.
[0037] In operation, a user plugs the hand-held system control unit
36 into an appropriate receptacle of the electrical interface
junction panel 30 and further plugs the motor assemblies 32 and 34
into the respective receptacles, thus completing a signal path
between each of the motor assemblies and the system control unit
36. Motion commands are provided to the system by the user, by
accessing the appropriate function provided on the hand-held system
control unit 36. Signals corresponding to the desired motion are
directed by the control unit 36 to the appropriate motor assembly
through the electrical interface junction panel 30. For example, if
a user desires to slew the telescope in a counter-clockwise
direction, he may enter a command into the control unit 36 telling
the telescope system to move "left". In response, the azimuth axis
motor assembly 32 is commanded to activate its integral motor in
order to rotate the telescope in a particular direction, thus
causing the telescope mount to pivot in a counter-clockwise fashion
about the azimuth axis 18. In like manner, when a user desire to
elevate the telescope 12 in an upwardly direction, the user would
enter the appropriate "up" command into the control unit 36 thus
activating the altitude motor assembly 34 which, in turn, causes
the telescope to pivot upwardly about the altitude axis 20.
[0038] Returning momentarily to the exemplary telescope embodiment
of FIG. 1, it should be understood that the telescope system
depicted therein comprises an integrated telescope such that the
altitude and azimuth motors are disposed within a vertically
positioned fork arm 22 and the telescope mount base 24,
respectively. Accordingly, there is no requirement to connect the
azimuth and altitude motors to the electrical interface junction
panel 30 in the particular embodiment of FIG. 1. Motor wiring is
accommodated internal to the structure of the mount (including the
fork arm 22 and base 24) and the system's electronic components are
packaged accordingly.
[0039] Turning briefly now to FIGS. 3a and 3b the mechanical and
electrical configuration of the electrical interface junction panel
embodiment of the telescope system of FIG. 2 are illustrated. It
can be understood from FIG. 3a that the interface junction panel 30
suitably comprises 4 RJ11-type connector receptacles with 3 of the
receptacles 38, 40 and 42 comprising 4-pin RJ11 connectors and one
of the receptacles 44 comprising an 8-pin RJ11 connector. In
addition to the RJ11 connections, the electrical interface junction
panel includes a "mini-pin" type 12 volt power receptacle 46 and a
visible "power present" indicator comprising an LED 48 mounted to
shine through a recessed opening in the panel located proximate to
the power pin 46.
[0040] FIG. 3b illustrates the electrical connections made between
and among the 4-pin RJ11 connectors, the 8-pin RJ11 connector and
the 12 volt power pin 46. External power is supplied to the various
connectors comprising the electrical interface panel 30 by a
suitable 12 volt power source 49 which might comprise a dedicated
12 volt battery pack or, alternatively, an adapter configured to
mate with a 12 volt automotive battery through, for example, a
power plug or a cigarette lighter. External power source 49 is
plugged into the 12 volt power pin 46 which takes the 12 volt
potential from the pins' center post and distributes it to pin 1 of
the 8-pin RJ11 connector 44 and the number 4 pin of each the 4-pin
RJ11 connectors 38, 40 and 42.
[0041] The 12 volt potential is reference to a return or ground
potential, by contacting a sleeve surrounding the center post in
conventional fashion and the reference potential is directed to the
number 8 pin of the 8-pin RJ11 connector 44 and the number 1 pin of
the 4-pin RJ11 connectors 38, 40 and 42. In addition, a 12 volt
supply is dropped across a series-configured resistor 50 and LED
diode 48 combination such that the 48 emits when a power supply is
present. Thus, a user is able to determine how the system is
powered up by examining the LED 48 disposed in the recessed opening
of the electrical interface junction panel.
[0042] In addition to power and ground, each of the 4-pin RJ11
connectors 38, 40 and 42 further comprise a 2-conductor serial
signal path with pin number 3 of each of the connectors identified
to a serial signal termed "CLK" and pin number 2 of each of the
connectors identified to a serial signal termed "DATA". A first
4-pin RJ11 connector 38 is configured as a connector for supporting
various pieces of auxiliary equipment and its serial signal lines
are correspondingly each identified as "AUX". The CLK and DATA
signals comprising pins 3 and 2 respectively are identified as AUX
CLK and AUX DATA respectively. Likewise the next 4-pin RJ11
connector 40 is configured to provide serial CLK and DATA signals
to the altitude motor assembly (alternatively a declination motor
assembly) and its CLK and DATA signal lines are thus denoted ALT
CLK (dec CLK) and ALT DATA (dec DATA), respectively. The next 4-pin
RJ11 connector 42 is configured to provide serial CLK and DATA to
the azimuth motor assembly (alternatively a right ascension motor
assembly) and its CLK and DATA signals are denoted accordingly.
[0043] The interface junction panel 30 described in connection with
the exemplary embodiments of FIGS. 3a and 3b is devised to be
suitable for use in connection with the exemplary telescope
embodiment of FIG. 2. Since the telescope embodiment of FIG. 1 does
not require external connections to be made to its motor systems,
the interface junction panel comprising the telescope system in
FIG. 1 need not include the 4-pin RJ11 connectors which couple to
the motor assemblies 32 and 34. Thus, the interface junction panel
of the telescope system in FIG. 1 would include an 8-pin RJ11
connector for coupling to a command module 36 and 1 or more 4-pin
RJ11 connectors for coupling to a plurality of auxiliary components
through one or more "AUX" ports.
[0044] Thus, it will be understood that the electrical interface
junction panel provides a means for routing power and control
signals between and among an external power source, a control unit
and various optional auxiliary pieces of equipment, such as
electronic focusers, electronic leveling devices, a global
positioning system receiver, and the like. So long as the auxiliary
equipment is configured to communicate over a serial signal buff
which supports clock and data signals.
[0045] In the context of the invention, both the telescope system
embodiments of FIG. 1 and FIG. 2 are fully automated with
distributed intelligence in that high-level user commands entered
into the command unit 36 which in turn translates high-level user
commands into appropriate commanded control signals suitable for
action by the motors. Each motor is itself intelligent in that each
motor is associated with a motor controller circuit which receives
command and control signals from the command unit 36 and
manipulates motor motion in response. Each of the motors are in
turn, coupled to a motion feedback evaluation device, such as an
optical encoder assembly, so that the actual travel of each
respective telescope axis can be evaluated against commanded travel
such that the position of each axis (and thus the telescope aspect)
is determinable with particularity.
[0046] The intelligent motor controller is also responsible for
slewing the motors at the proper slew rate by evaluating the speed
of axial displacement and controlling motor speed
correspondingly.
[0047] The aforementioned features of the fully automated
intelligent telescope systems of FIGS. 1 and 2 are described in
detail in co-pending patent application Ser. No. 09/428,866,
entitled "Fully Automated Telescope System Distributed
Intelligence," filed Oct. 26, 1999, and commonly owned by the
assignee of the present invention, the entire disclosure of which
is expressly incorporated herein by reference.
[0048] One particular embodiment of a hand-held control unit
suitable for use in combination with an automated telescope system
is depicted in FIGS. 4 and 5. FIG. 4 is a front view of the
exterior portion of a semi-intelligent drive motor motion control
unit 70 illustrating the various function keys that might be used
by a user of a telescope system in order to command a telescope to
move through various evolutions. The motor control unit 70
comprises a hand-held, self-contained, computer control unit,
enclosed within a functional housing. The motion control unit is
operational as a dual-axis motor drive corrector which enables
telescope axis motor motion, from the very small tracking
corrections necessary for long exposure astrophotography at
sidereal rates, to the very fast slewing movements required for new
object acquisition. The motion control unit supports motor movement
commands from microslewing a telescope to, and for precision
centering of a telescope onto, selected celestial objects. In
addition, the motion control unit 70 is able to command certain
special movement functions such as selecting various drive rates
for the telescope motors, adjusting an optional electronic focuser,
and the like. Further, and in accordance with the present
invention, the motion control unit 70 is able to perform a variety
of object acquisition and tracking functions which permits an
automatic telescope system to automatically track desired celestial
objects. As will be described in greater detail below, the motion
control unit 70 contains sufficient processing power in order to be
able to track objects with unusual celestial rates, such as the
lunar rate.
[0049] The internal construction of the semi-intelligent drive
motor motion control unit 70 is illustrated in the schematic
diagram of FIG. 5. As can be seen, the operational heart of the
motion 20 control unit 70 is an EPROM/ROM based 8-bit micro
controller 88 exemplified by the PIC16C54, manufactured and sold by
Microchip Technology, Inc. Function keys provide inputs to the
micro controller 88, which, in response, develops control output
signals which are directed to an 8-pin output header 90 having a
pin configuration which corresponds to an 8-pin RJ11 connector (44
of FIG. 3b) of an electrical interface junction panel, to which the
motion control unit 70 is intended to be connected.
[0050] In response to various direction, speed, focus and mode
commands input to the micro controller 88, the micro controller
develops and outputs control signals for the altitude motor, the
azimuth motor and a control signal pair coupled to the auxiliary
bus. Movement, speed, focus and mode commands are received by the
micro controller 88 and appropriate output control signals are
developed thereby in accordance with a software or firmware program
hosted by the micro controller and conventionally stored in an
internal memory space such as a programmable ROM memory.
[0051] In addition to receiving direction, speed, focus and mode
commands, the micro controller 88 is adapted to differentiate
between Northern and Southern hemisphere operations and between
equatorial and Alt-Az tracking modes. Jumpers, or some other such
signal delineator, differentiate between Northern and Southern
hemisphere operations by their presence or absence, respectively.
For example, Southern hemisphere operation might be defined by the
presence of a jumper in a first jumper position 92 which completes
an electrical short and asserts an I/O active state on identified
inputs to the micro controller. For Northern hemisphere operations,
the jumper might be absent from the first jumper position, thereby
placing the appropriate input into an I/O inactive state.
[0052] Likewise, equatorial and Alt-Az operational modes might be
differentiated by the presence or absence of a jumper in a second
jumper position, respectively. Alt-Az mode might be defined by
shorting the jumper position, thereby asserting an I/O active
state, while equatorial mode might be indicated by an I/O inactive
state.
[0053] With regard to communication between micro controller 88 of
the control unit and the semi-intelligent motor assembly, commands
are provided in serial fashion to the motor assembly in accordance
with a packet communication protocol, wherein each command packet
comprises one or more bytes of information with each information
byte being sequentially clocked into the receiving micro
controller, bit-by-bit, by a serial clock signal. In accordance
with practice of principles of the invention, each motor assembly
is directly coupled to the control unit's micro controller 88 via a
2-wire serial interface connection through the control unit's
header 90 and, thence to appropriate I/O pins of the micro
controller. Thus, information being communicated between a control
unit and a motor assembly need not be preceded with header
information. However, since the auxiliary serial interface is able
to host a multiplicity of auxiliary apparatus, information being
connected between a control unit's micro controller 88 and a
particular piece of auxiliary apparatus, needs to be preceded by an
address header in order to identify the information's intended
recipient.
[0054] With regard to motor motion commands, these commands are
issued directly to the motor assembly's micro controller over the
corresponding 2-wire serial interface. Motor motion commands, more
correctly termed step rate commands, are identified in hexadecimal
as (00 h) and comprise three bytes of information. The step rate is
defined as the number of steps or "ticks" that occur approximately
every 6 milliseconds during motor operation. The format is a two's
compliment number with the first number representing the whole
steps or "ticks", the next two bytes representing the fractional
portion thereof. Each step right command includes a sign (.+-.)
which determines the direction of motor motion.
[0055] A second step rate command, denoted (01 h) in hexadecimal is
formatted substantially identically with the (00 h) command but is
used for step rates greater than 2.times. the sidereal rate.
Additional information communicated between the control unit micro
controller and the motor assembly micro controller include a
"change error count" command (02 h) which commands a one time
change of the motor micro controller error count register.
[0056] Additional commands such as "turn on motor in positive
direction" (06h) and "turn on motor in negative direction" (07 h)
are also provided by the control unit the motor assembly's micro
controller. A "status" (08 h) command is read from the motor
assembly's micro controller and is typically three bytes in length
and further includes a flag bit. The first two bytes of information
comprise the determined change in motor position since the last
status read. The next byte comprises the PWM pulse count which is
used to determine whether or not the motor is in a stall condition.
The final bit, the flag bit, is an illegal encoder flag which
indicates that an encoder "tick" was missed during the current
motor position change. This bit is typically reset after a data
read, as is the determined motor position information.
[0057] Those familiar with the internal construction and
operational programming of a PIC 16C5X series micro controller, or
any equivalent micro controller for that matter, will be able to
routinely develop additional applications and command sets suitable
for, for example, developing a digital clock, controlling a key
pad, performing arithmetic calculations, and the like. All that is
required in practice of principles of the invention, is that the
control unit micro controller be able to communicate with one or
more motor assemblies so as to command motor speed and direction
changes which the motor assembly is able to execute. Further, the
control unit micro controller is able to communicate with one or
more motor assemblies so as to obtain feedback information as to
the extent of motor motion, such that the control unit micro
controller can calculate a telescope system's vector motion
(direction and speed) with respect to the celestial sphere.
[0058] The control unit translates keypad information into motor
motion commands, the motor assembly receives the motor motion
commands and causes the required amount of telescope motion about
its axes. Command and status information are communicated between
the control unit and the motor assembly via a 2-wire serial
interface in accordance with a packet communication protocol. The
control unit is able to determine that its commands have been
appropriately executed by evaluating return status information from
the motor assembly. Appropriate telescope motion, in response to a
motor movement command, is ensured by evaluating feedback signals
developed by an optical encoder system mechanically coupled to the
motor, electronically evaluated by the motor assembly's micro
controller unit, and provided to the control unit as tracking
computational input.
[0059] Each component coupled to the system comprises its own
operational intelligence and requires only a serial command
interface to a controlling entity to perform its designated
functions. Since each component comprises sufficient intelligence
(processing power) to execute its tasks without higher level
supervision, the controlling entity is free to execute application
programs, perform complex arithmetic calculations, maintain
database entries, and the like.
[0060] An additional embodiment of the hand-held control unit
suitable for intelligent control of a telescope system according to
the invention, is illustrated in FIGS. 6 and 7. FIG. 6 depicts the
exterior of an intelligent telescope system controller as it would
appear to a system user, while FIG. 7 illustrates in semi-schematic
block diagram form the configuration of the electronic components
which provide functionality to the controller 100.
[0061] FIG. 6 is a front view of the exterior portion of an
intelligent telescope system controller 100 illustrating the
various function keys that are used by a user of the telescope
system in order to command a telescope to move through various
evolutions. The intelligent controller 100 comprises a hand-held
package which functions as a full-spectrum control unit capable of
intelligently defining and commanding motor movements required for
astronomical observations, as well as for implementing their pre
and post processing features in a manner similar to a micro
computer.
[0062] The intelligent controller 100 suitably comprises an LCD
display screen 102 capable of displaying text, numeric and graphic
output data in a form that might be consulted by a user in
operating the telescope system. All prompts, user queries,
confirmation messages and the like are displayed on the LCD screen
102.
[0063] Telescope motion direction keys 112, labeled with
directional arrows indicating up, down, right and left, provide the
necessary inputs for enabling the telescope system to move or
microslew in the specified direction at any one of a number of
allowable, sentible speeds. As was described previously, the number
of allowable speeds which can be commanded to the semi-intelligent
motor assembly is limited only by the number of speed bits
comprising the speed and direction command. In the particular
embodiment being described, the number of allowable speeds that can
be commanded to a semi-intelligent motor is 8, with one of the 8
allowable speeds being reserved for the motor stop command. Once
the desired speed is selected, the desired motion direction key 112
is depressed and the system command the corresponding
semi-intelligent motor to move the telescope system at the desired
speed in the desired direction.
[0064] Scroll keys 106 and 108 are provided in order that a user
can scroll through a database listing or through available menu
options that might be shown on the LCD display screen 102. An enter
key 113 selects a file menu option or function or is used to define
the completion of an entry made in response to a system prompt. A
mode key 114 allows the user to exit the current menu in order to
return to a previous menu while a go-to key 115 commands the
telescope system to slew the telescope to an object chosen from an
internal celestial database listing.
[0065] The internal construction of intelligent telescope system
controller 100 is illustrated in the semi-schematic block diagram
of FIG. 7. As can be seen, the intelligent controller, indicated
generally at 100, suitably comprises a dual processor system, with
a dual processing function implemented with a first, general
purpose micro processor 120 exemplified by the 68HC11, a member of
the 68HCxx family of microprocessors manufactured and sold by
Motorola Corporation, and a second purpose configured
microprocessor or microcontroller 121 exemplified PIC16C57
microcontroller manufactured and sold by Microchip Technology,
Inc.
[0066] The general purpose microprocessor 121 is coupled to a
16-bit address and data bus (AD[0,15]) and an 8-bit data bus
(D[0,7]) which allows the microprocessor 121 to communicate with a
programmable read-only memory (ROM) circuit 124 and random access
memory (RAM) 126. Further, the 4 most significant bits of the data
bus (D[47]) are coupled to the system's LCD display driver circuit
127 in order to provide an interface between the microprocessor 121
and the system's LCD display 120.
[0067] As will described in greater detail below, the
microprocessor 121 is responsible for implementing the top-level
firmware architecture of the system according to the invention and
for executing suitable application software routines pertinent to
the exemplary intelligent telescope system.
[0068] Programmable read-only memory circuit 124 is preferably
implemented as a FLASH programmable ROM and is provided in order to
host the instruction set for downloaded applications and software
routines, data tables such as a stellar object position database,
the Messier object catalog list, an earth-based latitude/longitude
correspondence table and the like. Although described as an FPROM
the ROM memory may be implemented as an EEPROM or any other type of
programmable non-volatile memory element. Indeed the ROM 124 might
be implemented as an external mass storage unit such as a hard
drive, a programmable CD/ROM and the like. All that is required is
that the memory 124 be able to be written to in order that its
hosted databases and tables may be updated, and be non-volatile in
order that its hosted databases and tables be available to the
system upon boot-up or power-on-reset.
[0069] Microprocessor 121 is further coupled to the microcontroller
122 over a control bus 123 which, in turn, is coupled to the
various function keys (indicated generally at 132) by a
multiplicity of interface signal lines. In this respect the
microcontroller 122 function as the system I/O and interface
controller which translates use input taken from the keypad and
provides command and control signal, derived from the user input,
to the system microprocessor over the interface bus 123.
[0070] The system microprocessor 121 is further coupled to RS-232
interface port circuitry 128 over a serial bi-directional interface
bus 133. The RS-232 port circuitry 128 is in turn coupled to an
RS-232 interface connector 129, through which bi-directional
communication between the microprocessor 121 and an external
information source such as a personal computer (PC), a world wide
web (WWW) interface link, and the like maybe effected.
[0071] Indeed the RS-232 port 128 may be configured to communicate
with a similar RS-232 port comprising another separate intelligent
controller system operating in conjunction with another separate
telescope system. It will be understood that, when operating under
appropriate I/O control application firmware the microprocessor 121
in connection with the RS-232 port 128 provides means for quickly
and easily interfacing the system to an external source of program
code, data or other information that a user might desire to
incorporate into the instructions or data tables comprising the
intelligent controller of the present invention.
[0072] Likewise, the microcontroller 122 is coupled to a bundled
serial interface connector 130 suitably comprising an 8-pin RJ11
type interface suitable for connection to the 8-pin receptacle of
the electrical interface panel of the telescope system. The
interface connector is configured to support connections between
the microcontroller 122 and 2 telescope axis drive motors, along
with a plurality of auxiliary devices, over respective serial
interface busses. So configured, the PIC16C57 microcontroller 122
will be understood as interfacing between the user I/O interface
keys 132 and the 68HC11 microprocessor 121, to generate command and
control signals suitable for use by a semi-intelligent motor and/or
an auxiliary device, such as an electronic focusing system or GPS
receiver operating in accordance with the NMEA interface standard,
and provide such command and control signals to the electrical
interface panel for routing to their appropriate destination.
[0073] In accordance with the present invention, the 68HC11
microprocessor 121 performs the high-level application execution
tasks and the associated data handling and numerical processing, in
order to define the appropriate motor motion commands to be
provided to the PIC16C57 microcontroller 122. The microcontroller
122 receives motion command inputs from either the microprocessor
121 or the user interface keys and suitable processes the received
motion commands into commanded control signals suitable for use by
a motion control processor.
[0074] To complete the system and to give the microprocessor 121
some means of performing time calculations appropriate to celestial
motion, a real time clock is provided and is coupled to a clock
input of the microprocessor 121, as well as being coupled to the
clock input of the microcontroller 122. The real time clock 138 is
preferably implemented as a precision timing reference clock signal
generator, such as a UTC clock that is used by the microprocessor
121 to calculate sidereal time intervals and preferable resides as
an integral component of the control unit 100. Alternatively, the
clock 138 might be implemented as a separate off-board integrated
circuit comprising a conventional UTC clock which communicates with
the system over the RS-232 interface or an on-board UTC clock and
follow-on circuitry for converting UTC time intervals to sidereal
time intervals prior to providing a timing reference to the
microprocessor 121.
[0075] It should also be understood that a GPS receiver is able to
provide timing signals which can function as precision timing
reference signals in a manner similar to a UTC clock. Coupling a
GPS receiver to the system according to the invention enables the
control unit 100 to receive not only coordinated timing data but
also user position data from a single external apparatus coupled to
the system either through the auxiliary port or over the RS-232
interface.
[0076] Thus, it should be understood that the intelligent telescope
system control unit 100 suitably comprises a means for adding full
intelligence to a telescope system which includes semi-intelligent
motors, in accordance with the present invention. The intelligent
telescope system controller performs this function by bifurcating
the system's processing and control functions into a first
sub-system comprising a microprocessor operative for system data
processing, and a second microcontroller system, for implementing
I/O control. System intelligence is maintained up-to-date by
allowing "new object" loadability through an RS-232 port. System
software, updated celestial object catalog tables and the like, may
be loaded into the system through the RS-232 port from a PC, an
attached disk or disk drive, a website, a separate intelligent
telescope system controller in accordance with the invention, and
the like.
[0077] Beyond support of system utilities, the intelligent
telescope system controller is also able to support a multiplicity
of auxiliary devices that might be coupled to the telescope system
in order to enhance its capabilities. Pertinent such devices
include automatic focussing unit; a clock and date module, a speech
recognition module along with an associated audio output module, an
automatic alignment tool (tube leveler and/or axis planarizer), a
global positioning system (GPS) module, a photometer, an
autoguider, a reticule illuminator, a cartridge reader station (for
courseware, the revisions, new languages, object libraries, data
storage), and the like. Each auxiliary device is coupled to the
system, in daisy-chain fashion, over the AUX DATA and AUX CLK
signal lines comprising the auxiliary bus system or alternatively,
over the RS-232 port.
[0078] The full spectrum of the auxiliary device command set can be
easily implemented in the intelligent system controller because of
the capability range of its microprocessor 121. It will be
understood that the full spectrum command set may be incorporated
in the microprocessor by a reasonably proficient programmer, making
the intelligent system controller 100 capable of supporting the
full spectrum of auxiliary devices. A reduced set of auxiliary
device command sets are implemented in the semi-intelligent system
controller (70 of FIGS. 4 and 5) because of the relatively limited
capability of its microcontroller 88, with respect to the
capabilities of the fully intelligent system. In deed the auxiliary
interface bus provides a particular enabling feature for system
upgrade capability, by virtue of its simplicity and the inherent
expandability of its serial bus concept. Adding capability to the
telescope system of the invention is as uncomplicated as merely
coupling additional devices to the bus. The bus then provides the
framework within which intelligence and capability are added,
subtracted or modified on a piece-by-piece basis.
[0079] Each component coupled to the system comprises its own
operational intelligence and requires only a command interface with
a controlling entity in order to perform its designated function.
Since each component comprises sufficient intelligence (processing
power) to execute its tasks without higher supervision, the
controlling entity is free to execute application programs, perform
complex arithmetic calculations, maintain database entries, and the
like without being unduly tasked by peripheral control
functions.
[0080] In particular, the hand-held control unit performs high
level application software execution tasks and associated data
handling and numerical processing, in order to define appropriate
motion commands which are to be provided to the telescope system's
semi-intelligent motor modules. The motor modules suitably process
the received motion commands into command and control signals
suitable for operating the motors. In combination, the
semi-intelligent motor controller and the hand-held control unit
are able to execute a variety of telescope orientation and object
tracking functions in a straight forward and inexpensive
manner.
[0081] Primary control of an automated telescope system with
distributed intelligence, in accordance with the present invention,
is provided by a fully intelligent telescope system controller.
Substantially all functions of an automated telescope system can be
implemented through the keypad portion of the controller 100 by
depressing the various alpha, numeric and function keys provided
thereon. Once the automated telescope system has been appropriated
aligned, as will be described in greater detail below, an object
menu library, stored in a dedicated memory space provided in the
controller, is used to automatically slew the telescope system to
any particular celestial (or terrestrial) object an observer
desires to view or photograph.
[0082] However, prior to beginning an observation and indeed during
initial set-up of the system, the user must first initialize the
system entering certain information in accordance with an
initialization or set-up procedure which can best be understood
with reference to the initialization procedure flow chart of FIG.
8.
[0083] After each of the individual components comprising the
system are connected together, the intelligent controller 100 is
plugged into the control unit port and power is provided to the
system. Following "power-on-reset", the system controller prompts
the user to enter the current date, by entering the appropriate
figures in formatted date field. An exemplary date field might
appear as "Jan. 1, 2001", numeric values such as the date and year
are entered by depressing the corresponding numeric keys of the
numeric keypad when prompted to do so by the system. The current
month is entered by scrolling through a list of months using the up
and down arrow keys provided for that purpose. In particular, the
date cursor automatically jumps to the next space once particular
numeric value is entered. If a mistake is made during entry, the
right or left directional keys may be depressed to move the cursor
backward or forward until it is positioned over the incorrect
entry. The correct entry may then be made by depressing the
appropriate numeric key on the numeric keypad 104.
[0084] After all of the date information has been correctly
entered, the system prompts the user to enter the current time. It
should be noted that the system is operative in a 24-hour mode and
therefore time should be entered using a 24-hour clock (i.e. 9:00
p.m. is entered as 21:00). This procedure is very useful in
enhancing the precision of positioning calculations undertaken by
the system by giving the system a more precise indication of the
correct time. Needless to say, the more precise the time indication
provided to the system, the better the system will be able to
locate objects on the basis of their published right ascensions and
the better the system will be able to accurately position the
telescope to view them.
[0085] At this point, the positioning keys 112 of system controller
100 are activated such that they can be used to move the telescope.
The user is able to either immediately proceed using the telescope
without further initialization data entry or a user may continue
with data entry in order to enable additional features of the
inventive system. If a user chooses to continue with
initialization, a next procedure displays the status of a daylight
savings time feature. Daylight savings time is in effect from the
first Sunday in April through the last Sunday in October in most
areas of the United States and Canada. Users are cautioned to
investigate whether their geographic local time conforms to
daylight savings time or not.
[0086] A next sequence of data entry operations enables a
particularly novel orientation feature in the present invention
wherein an observers latitude and longitude are approximated by the
latitude and longitude of the closest city of geographical land
mark which a user may designate as reasonably approximating the
observation location. For example, the next procedural step causes
the LCD display to request entry of the nation, state or province
of the user's primary observation site. The scroll keys are used to
scroll through a list of various countries, states and provinces
contained in the system's database until the observer's nation,
state or province appears on the screen.
[0087] Following selection of the observer's nation, state or
province, the observer is requested to select the closest city or
major geographical feature to their primary observation location by
using the scroll keys to cycle through an alphabetical list of
cities and geographical features. When the desired city or feature
is displayed on the screen, the user depresses the enter key in
order to inform the system that the virtual location procedure has
been concluded. The geographical coordinates (latitude and
longitude) of the select site are then entered into system memory
as a first approximation observation location indicia which is used
in combination with the current time in order to orient and align
the telescope system for fully automated use.
[0088] This virtual location procedure is enabled by a database
table comprising a multiplicity of alphabetically listed geographic
locations with each location associated to their known latitude and
longitude coordinates, as depicted in FIG. 9. FIG. 9 illustrates a
partial database listing of an exemplary-level location table and a
sub-level database listing for locations contained within the
indicated California entry. The location database listing is
typically stored in the system's ROM memory, but might
alternatively be stored in an external disk drive, a floppy
diskette or some other such mass storage device. So long as the
location database listing is stored in some non-volatile memory
such that it may be accessed at need upon system power-up. Such a
virtual location procedure will be considered advantageous,
particularly when one considers that the location of a particular
celestial object in the night sky, at any given time, is solely a
function of the observer's latitude and the observer's local hour
angle displacement from the celestial meridian, in turn a function
of the observer's longitude and the observer's local time-of-day
(also known as local hour angle). Thus, once an observer's latitude
and longitude are known, as well as the time-of-day (expressed in
universal time coordinates), the observer has all the information
necessary to compute the relative bearing, in either altitude and
azimuth or declination and right ascension of any celestial object
whose absolute coordinates are known. When an observer enters a
reasonable approximation of his latitude and longitude, and enters
his local time, the system is able to reasonably approximate the
orientation of the night sky with respect to that observer. As will
be described in greater detail below, further corrections may be
made to this "first approximation" orientation procedure in order
more precisely and accurately define the night sky with respect to
the telescope's orientation.
[0089] Alternatively, the entire initialization procedure described
in connection with the exemplary flow diagram of FIG. 8 may
dispensed with by the simple expedient of coupling a global
positioning system (GPS) receiver to either the auxiliary port or
the RS-232 port of the telescope system and using the data provided
by the GPS receiver in place of manual data entry. GPS receivers
are manufactured by a variety of commercial venders and are
available to the general public in small units costing as little as
$100.00. GPS receivers are able to provide latitude and longitude
information, as well as coordinated timing information, over a
signal bus in accordance with a generally accepted communication
standard, such as NMEA. In this manner, date and time information
as well as the observers latitude and longitude are made available
to the system in electronic form over a simple electronic
interface. Even a daylight saving time indication may be dispensed
with since the system is able to evaluate the latitude and
longitude information provided by the GPS receiver and determine
whether the user is in the United States or Canada during the
requisite time period at which daylight savings time is operative.
Thus, coupling a GPS receiver to the system further simplifies the
system's initialization procedure, making systems of this type
easily accessible to persons with no prior knowledge of
astronomical observation techniques.
[0090] There are two fundamental considerations that must be given
to any fully automated telescope system in order for that system to
be useful to the observer. The first is that the telescope
(particularly a telescope configured as an altitude/azimuth
telescope) must be able to operate in accordance with the celestial
coordinate system expressed in right ascension and declination
coordinates (understand the congruence of rectangular coordinates
with spherical coordinates). Secondly, once a particular object,
expressed in celestial coordinates, has been acquired the system
must be able to track that object's motion through the sky.
Therefore the processing power of the intelligent telescope system
in accordance with the invention, is directed toward implementing
these two fundamental operations: objection acquisition and object
tracking. The first operation is enabled by orienting the telescope
system with the night sky.
[0091] One particular embodiment of an orientation or alignment
methodology in accordance with the practice of the invention, is
described in connection with the procedural flow chart of FIG. 10.
Specifically, when the alignment procedure is selected from a
prompt screen, the system prompts the user to move the telescope
(using motion keys 112) until the telescope is pointed in the
direction of north. It should be mentioned that the telescope could
also prompt the user to move the telescope until it is pointed in
the direction of south, if the user is in the southern hemisphere
and south is the more appropriate direction. After the telescope
tube is pointed toward the north, a user depresses a function key
in order to inform the system that the telescope tube is in its
appropriate position. Next, the system prompts the user to level
the telescope tube by adjusting the telescope's altitude position
until it is pointed towards the horizon. Pointing the telescope in
a particular compass direction such as north and leveling the
telescope tube, functions to zero-in the position encoders of the
altitude and azimuth motor assemblies. Any subsequent motion of the
telescope away from its zero, zero position allows the telescope
system to directly calculate its altitude and azimuth displacements
from the zero, zero reference point.
[0092] Using the time and date entries either input by the user or
acquired from a GPS receiver, the telescope system consults a data
base of well-known celestial objects and selects a particular
bright object which is currently above the horizon. The time and
date information allows the system to calculate whether that
particular bright object has rotated sufficiently in right
ascension to bring it above the observer's horizon, while the
latitude and longitude entry, either provided by an observer or
acquired from a GPS receiver, provides the system with sufficient
information regarding an observer's latitude such that it may
calculate an approximate declination value for that bright
object.
[0093] Once an object (such as a star) is identified in the data
base, the system automatically slews the telescope to the vicinity
of that star by commanding the appropriate motion from the altitude
and azimuth motors. Once the telescope has slewed to the vicinity
of the desired star, the observer is prompted to center the star in
the field of view of the telescope eyepiece. When the star is
centered, the observer depresses a function key and the system then
searches the data base for a second bright object or star which is
displaced at least 30.degree. from the previous star in order to
increase the accuracy of the orientation or alignment procedure.
Once the second star is identified from the data base, the system
automatically slews the telescope to the vicinity of that star and
once again prompts the user to center that star in the field of
view of the eyepiece. When the second star is centered, the system
calculates the position and orientation of the telescope with
respect to the night sky (the celestial sphere).
[0094] A further, truncated, alignment and orientation procedure is
depicted in the exemplary flow diagram of FIG. 11, in which an
Alt-Az configured telescope is oriented to the night sky using only
a single star alignment procedure. As with the previous case, a
user is prompted to zero-in the motor position encoders by pointing
the telescope toward the north (or south) and leveling the
telescope by pointing the tube at the horizon. The user then
selects a particular star from an alphabetized stellar object data
base list and presses a function key which causes the telescope to
automatically slew to the vicinity of that star. The user centers
the star in the field of view of the eyepiece by depressing the
position keys 112 as required. Once the chosen star is centered in
the field of view of the eyepiece, the user again depresses a
function key and the telescope is aligned for a night of
viewing.
[0095] The telescope is technically considered "aligned" or
"oriented" after the user follows the above-described alignment
procedure. However, the accuracy of a single star telescope
alignment procedure should only be considered sufficient for
general astronomical observations. Because of certain pointing
errors that occur as the result of well-known astronomical
perturbations, additional observations from the basis for third,
fourth, fifth and higher order refinements to the accuracy of the
alignment or orientation procedure.
[0096] Once the absolute position of the telescope system with
respect to the night sky is determined, the system microprocessor
112 is easily able to calculate the path of any given celestial
object through the sky, and to develop the appropriate motor motion
commands, in accordance with well-known drive rate equations to be
described in greater detail below, such that an Alt-Az telescope
system can smoothly and accurately track the object, i.e., "stop
the sky" in software. A celestial object's motion through the sky
will, necessarily, be calculated in terms of its rate of change in
both altitude and azimuth as a function of time. Thus, for a given
period of time, the system microprocessor 121 is able to calculate
the incremental motor motion or "tick" rates required to be
executed by the motor so as to allow the telescope to attract the
object as it moves through the sky.
[0097] With regard to the foregoing alignment procedures described
in connection with the orientation flow charts of FIGS. 10 and 11,
it should be noted that the system controller calculates the
telescope's position by mapping the telescope's Alt-Az coordinate
system (Cartesian coordinate system) to the RA and Dec spherical
coordinate system defining the night sky (celestial sphere). In
particular, the system controller reads the telescope's altitude
and azimuth angular positions, when pointed at the selected star or
stars, by reading the altitude and azimuth motor position encoder
values after each star has been centered in the telescope eyepiece.
From the telescope pointing angles thus defined, the system
controller calculates the telescope's Cartesian position vectors
and resolves each position vector into a matrix of direction
cosines. The Cartesian coordinate matrix is mapped into a similarly
defined matrix of the direction cosines of the star or stars
expressed in terms of the spherical coordinate system, using well
understood mathematical techniques involving matrix manipulation
and rotation. The matrix of celestial direction cosines is
generated by evaluating the RA and Dec coordinates of the star or
stars identified by the user during the selection procedures. It
will be evident to those familiar with mathematical arts that once
the same two points are identified in two different coordinate
systems, those two coordinate systems can be mathematically mapped
to one another such that any further coordinates expressed in one
coordinate system are easily expressed in the other coordinate
system through a mathematical transform. Thus, once the telescope
system is aligned with respect to the celestial sphere, further
observations may be made by merely expressing the location of the
desired object in terms of its celestial coordinates. The system
controller understands the relationship between the celestial
coordinate system and the telescope's altitude and azimuth
coordinates, makes the proper mathematical transformation, and
drives the altitude and azimuth motors appropriately in order to
point the telescope at the desired celestial position.
[0098] Notwithstanding the alignment and orientation procedures
described above, the fully automated telescope system in accordance
with the invention is able to implement object tracking procedures
without regard to formal alignment and orientation. Specifically,
the intelligent telescope system is able to track any selected
celestial object having recourse only to a good approximation of an
observer's latitude. It is a well understood concept that a
celestial object's motion through the sky will be a function of an
observer's latitude and, once an objection's initial motion vector
is defined, that object's radial travel path can be calculated.
Once the travel path has been calculated, that object may be
"tracked" throughout its motion across the night sky.
[0099] The solution to any given problem in celestial trigonometry
depends on being able to convert measurements obtained in one
coordinate system (Alt-Az, for example) into the other coordinate
system (the celestial coordinate system for example). Coordinate
system transformations are well understood by those having skill in
the art, indeed, have also undergone a conceptual evolution,
culminating in modern day, computer assisted, matrix transformation
and rotation mathematics. Nevertheless, regardless of the
coordinate systems used to express an observation and the
coordinate system used to define a universal reference,
observations made in one coordinate system may be rotated into the
reference coordinate system using simple mathematical principles,
so long as two points in one coordinate system correspond to the
same two points in the other coordinate system, such that
transformation boundaries with respect displacement and rotation
are defined. Thus, two reference points expressed in an Alt-Az
coordinate system, for example, are a necessary and sufficient
condition for the Alt-Az coordinate system to be rotated into a
celestial coordinate system, so long as those same two measurement
points have a corresponding location metric in the celestial
coordinate system. Tracking an object is conceptually a rather
simpler exercise, and involves "stopping the sky" in software by
driving the telescope axes in accordance with the following
equations: d Z d h = 15 .times. .times. sin .times. .times. A
.times. .times. cos .times. .times. .PHI. EQUATION .times. .times.
1 d A d h = - 15 .times. ( sin .times. .times. .PHI. + cot .times.
.times. Z .times. .times. cos .times. .times. A .times. .times. cos
.times. .times. .PHI. ) EQUATION .times. .times. 2 ##EQU1##
[0100] where Z is the calculated zenith distance of an observer, h
is the observer's local hour angle (or LHA), A is azimuth (measured
westward from south) and .PHI. is the observer's latitude. The rate
of change of an object's zenith distance Z with hour angle h and
the rate of change of an object's azimuth A with respect to hour
angle h is defined in units of (sidereal second).sup.-1. Thus, in
order for the telescope system to be able to adequately acquire and
track a given celestial object a first condition is that the
telescope system understand its orientation with respect to the sky
such that an observer's latitude and local hour angle (.PHI., h)
can be calculated.
[0101] Additionally, and in accordance with the invention, if an
observer's latitude and azimuth (.PHI., A) are known, an objects
zenith distance Z and respective motion (dh) can be first
approximated, and then calculated, by iterative solutions of the
drive rate equations. Since an objects proper motion, with respect
to the celestial hemisphere, depends on the latitude of an
observer, once an observer's latitude is defined, or approximated,
an automated telescope system is able to reasonably approximate,
and therefore track, any object whose zenith distance Z and azimuth
A is determinable.
[0102] In a first tracking procedure, a user need only indicate to
the telescope system, through use of a hand-held control unit
(referred to hereafter as a hand box controller) which hemisphere
(Northern or Southern) the observer is in. The observer next
commands the telescope system to manually move such that the
optical system is pointed in the direction of the corresponding
celestial pole (the pole star or Polaris in the Northern
hemisphere). This particular position is indicated as a starting
point for the tracking procedure, by signaling the hand box
controller with a set of pushbutton or key pad requests. Next, the
telescope system is lowered to a level position such that the
telescope optics are directed at an observer's local horizon. The
hand box controller is again signaled with a set of push button or
key pad requests indicating that this position is a second
reference point for the procedure.
[0103] Pointing the telescope optics first, towards the North
celestial pole, and the next at the horizon, sets two reference
points in the memory of the hand box controller unit. Slewing the
telescope system from the North celestial pole to the horizon
defines the angular displacement of the North celestial pole above
the horizon, which angular displacement corresponds to the
observer's latitude. Initializing the telescope system to an
observer's horizon will then allow the telescope system to capture
an object's zenith distance Z by a simple trigonometric subtractive
calculation.
[0104] Initializing the telescope system to the North celestial
pole further provides a zero reference point for azimuth A
calculations. Thus, it will be understood that initializing the
telescope system with respect to the North celestial pole and an
observer's horizon, provides all the requisite data necessary for
an instantaneous solution of the drive rate equations given above.
The hand box controller now has all of the information needed to
track any celestial object placed in the field of view of the
telescope system.
[0105] A simplified alignment and tracking procedure is patterned
along the lines of the preceding alignment system. As with the
previous case, a user indicates to the hand box controller which
celestial pole will be used for the procedure (i.e. whether the
observer is in the Northern or Southern hemisphere). The telescope
is slewed to a level position, pointing in the direction of the
pole (level and North or level and South) and the hand box
controller is signaled with a set of push button or keypad
requests. Signaling this information into the hand box controller
has the effect of initializing the azimuth A and altitude (Z or
90-Z) motor positions such that altitude and zenith distance of an
object are easily determinable. Latitude need not be affirmatively
calculated, so long as the system has some means of determining an
objectively reasonable, and reasonably accurate, observation
latitude.
[0106] In accordance with the principals of the present invention,
the hand box controller assumes that the telescope system is
positioned at a particular latitude of high probability, chosen by
a statistical analysis of world population distribution on a
hemisphere by hemisphere basis. In particular, in the Northern
hemisphere, latitude 38.degree. N offers a very high probability of
being close to an observer's actual latitude. Accordingly,
38.degree. N is chosen as the first approximation of a latitude
metric and used, initially, in the drive rate equations. Since the
latitude metric is an approximation, object tracking might not be
perfect, but even though an approximation, the system will
considerably lengthen the time an object remains visible in the
field of view of the telescope eyepiece.
[0107] A further tracking procedure can be implemented by the
automated telescope system according to the invention that can
function as a stand-alone tracking system, or as an iterative
correction methodology that can be applied to either of the two
previously described tracking procedures in order to refine the
variable data for the drive rate equations and so improve system
tracking. Although the telescope system might technically be
considered "aligned" after the user follows any of the
above-described alignment procedures, telescope tracking accuracy
should only be considered sufficient for general astronomical
observations. Because of certain pointing errors that occur as the
result of well known astronomical perturbations, additional
observations might be incorporated into the procedure to refine the
accuracy of the initialization procedure.
[0108] In particular, if a telescope is pointed at a particular
celestial object, or any object moving at a reasonably steady rate
in a definable direction, like an airplane, satellite, boat or
flock of geese, the telescope may be manually repositioned in order
to keep the objects centered in the eyepiece field of view. In this
particular circumstance, the hand box controller records the
movements commanded to the motors and uses the average corrections
to the motor motion commands to define a motion vector (angle and
speed) to create a continuous tracking motion. The telescope then
automatically tracks the selected object after a sufficient number
of altitude and azimuth commands have been received, to calculate
an average motion. Even when in automatic tracking mode, additional
corrections to the telescope position will continue to update the
average motion calculation and thus allow the telescope system to
more accurately track the object.
[0109] When used in combination with the simplified coarse
alignment procedure, above, minor corrections to the telescope
system's tracking motion are plugged-in to the drive rate equation
results and new, more precise values of an observer's latitude may
be calculated. In addition, further observations and tracking
corrections provide additional data points which are incorporated
into correction algorithms that compensate for pointing errors that
occur as the result of well known astronomical perturbations. As
additional observations and corrections are made, the system is
able to compensate for precession, refraction, as well as certain
mechanical errors introduced by imperfections in the telescope
mount, the motor and drive train system, the servo feedback system
and imprecisions in leveling the telescope.
[0110] In this regard, the first and second alignment procedures
might be viewed as creating a base speed and base direction which
might be used as an initial vector in the third procedure. This
permits method three corrections to be smaller and further permits
tracking to start immediately upon selection of an object by a
user.
[0111] The system hand box controller receives user 1/0
information, and performs any needed data processing under
application software program control. Data processing typically
results in some form of desired telescope motion with the system
being able to calculate the direction and extent of the required
motor motion and being further able to direct the appropriate motor
assembly to take the required action by passing the appropriate
command.
[0112] Notwithstanding the foregoing discussion of telescope
orientation and alignment, it will be evident to one having skill
in the art, that major simplifications can be made to a telescope
orientation and alignment procedure by incorporating additional
component devices that are able to automatically provide an
indication of the orientation of the telescope tube with respect to
the compass, i.e., North-South sensing, and an automatic indication
of axial tilt, i.e., telescope level. Given such ancillary devices,
an automated telescope system might be able to instantaneously
understand its orientation to and alignment with a celestial
coordinate system, given only an indication of an observer's
latitude. The observer's latitude can be determined either directly
by pointing the telescope system at a respective celestial pole, or
indirectly by following the proper motion of a known celestial
object and computing latitude from the drive rate equations.
[0113] Pertinent such additional component devices include an MR
sensor system, such as described in co-pending patent application
Ser. No. 09/428,866, entitled, "Fully Automated Telescope System
With Distributed Intelligence," filed Oct. 26, 1999, commonly owned
by the assignee of the present invention, the entire disclosure of
which is expressly incorporated herein by reference. Such an MR
sensor is able to electrically resolve a position orientation using
the earth's magnetic field, to an accuracy of approximately
0.5.degree. and with a resolution of approximately 0.1.degree.. As
is well understood by those having skill in the art, the earth is
surrounded by a magnetic field which has an intensity of from
approximately 0.5 to approximately 0.6 Gauss and includes a
component parallel to the earth's surface that always points
towards magnetic north. This feature of the earth's magnetic field
forms the basis for all magnetic compasses and it is the components
of this field, parallel to the earth's surface, which are used to
determine compass direction. Telescope level orientation is
accommodated by use of a level sensor, which may be provided
separately or which may be incorporated within the MR sensor. The
telescope system is thereby provided with a fully automated,
electronic methodology for 3-axis sensing. This allows the
telescope system to automatically adjust itself to a level
condition, as well as automatically adjust itself to align with
either a true or a magnetic north. Once these alignments are made,
the axis encoders of the motor systems are automatically
initialized in order to compensate for mount alignment parameters.
Therefore, electronic sensors coupled to the telescope tube provide
a very repeatable position index when in proximity with the mount's
axis crossings.
[0114] Further, accurate location information can be provided to
the intelligent system control unit by use of the global
positioning system (GPS) or differential global positioning system
(DGPS) receiver configured with an NMEA interface. The NMEA
interface is a well recognized interface protocol which can
additionally be coupled to the auxiliary interface or RS-232 port
to provide a source of location information directly to the
intelligent system control unit. Once the intelligent system
control unit has location, time and date information available, as
well as axial aspect information derived from the "north" and
"level" sensors, the intelligent system control unit becomes fully
aware, not only of its location, but also of the spatial
orientation of the telescope system to which it is coupled.
[0115] A further refinement to these orientation and alignment
systems can be made by understanding that a celestial object
follows a predetermined path in the night sky, which path may be
described by a relatively simple mathematical relation. Once an
observer's latitude is known, any celestial object, having a known
position RA and Dec, can be used to define an observer's longitude
(or local hour angle, or the like) by evaluating the objects actual
track through the night sky and solving its equation of proper
motion. The object's position on the proper motion curve is
necessarily a function of the observer's longitude. This derived
information can be incorporated with tracking measurements in order
to further refine a telescope system's alignment and orientation
data.
[0116] The foregoing procedure might be referred to as telescope
alignment on the basis of "drift alignment" of a particular
celestial object. Drift alignment refers to the monitoring of the
movement of any particular star and understanding the orientation
of the observation system based on the direction of movement and
magnitude of movement of the particular celestial object. Deriving
movement vectors, i.e. identifying direction and magnitude of
movement, can be performed manually by an observer's following the
motion of a celestial object with a telescope system. Celestial
object movement is signaled to the telescope's control system by
moving the control system using the slew keys of the hand box
controller in order to maintain the object in a relatively centered
position in the telescope eyepiece.
[0117] Particularly, and in connection with the illustration of
FIG. 14, it is well settled that a celestial object's apparent
motion defines a circular path about a centroid defining a
celestial pole and closely approximated by Polaris or the "Southern
Cross", for example. An observer O who is tracking a celestial
object, such as a star S, will move the telescope through an arc at
a particular rate (the sidereal rate), thereby defining an arc
length L. If the telescope is configured as an Alt-Az, the arc will
necessarily be approximated by small linear displacements in
altitude and azimuth. The root of the sums of the squares of the
displacement values will then define a hypotenuse of an isosceles
triangle, the other two arms of which each define the radius r of
the object's circular path about the celestial pole. The
hypotenuse, so defined, is a very-close approximation to the arc
length L moved through by the object. Knowing the sidereal rate and
the time taken between measurements allows the system to calculate
the angle .PHI. which subtends the arc. Given this information, the
system determines the radius r through the relation: ArcL=r.PHI..
Knowing r, the sidereal rate, and an object's instantaneous
position, the system has all the information necessary to derive
and solve that object's equations of motion, such that tracking
becomes fully automated. Minor corrections made by a user to
maintain an object in precisely the center of the viewing area
function to also refine the equations of motion, such that tracking
accuracy can be enhanced to any required degree.
[0118] Further, if the telescope system had been previously
referenced to the horizon, the altitude data, A1.sub.1 and
A1.sub.2, taken at two viewing positions of an object can be used
to define the observer's latitude, in background, by merely
tracking an object for a small period of time. Performing the
above-described tracking procedure defines an object's radial
distance r from a corresponding pole. Using well understood
trigonometric principles, the height h of the radial distance r is
calculated and the algebraic sum (h+r) describes the declination of
the corresponding celestial pole. Given this, an observer need only
slew to another arbitrarily selected celestial object and the
telescope, knowing only the object's declination, will begin
automatically tracking the object.
[0119] To complete the development, it will be further understood
that if the object is know, i.e., if its celestial coordinates are
identified to the system, the system has all of the information
necessary for total alignment and orientation of the telescope.
Evaluating two positions of a known object within a known time
interval, with the system according to the invention, corresponds
to evaluating two different known objects (the two object
methodology discussed above).
[0120] Turning now to FIG. 15, an object whose apparent motion with
respect to the telescope, describes an arcuate path A is tracked by
the telescope system by adjusting the telescope's altitude and
azimuth. For each adjustment required to maintain the object
substantially in the center of the viewing area, there will be a
corresponding change in altitude, a change in azimuth, or both. If
the object is traveling at a constant speed, the system is able to
define a rate of change of altitude as well as a rate of change of
azimuth and drive the axial motors accordingly. As an object's
arcuate travel path changes from a generally upward direction to a
generally downward direction, it will be understood that the
"change in altitude" parameter will change sign (i.e., move through
an inflection point). This allows the system to develop a
prediction of an object's travel path even if the travel path is
relatively complex.
[0121] Alternatively, deriving an object's movement vector might be
performed automatically if the telescope system is coupled to an
electronic imager which, in turn, supplies movement magnitude and
direction information to the hand box controller. An electronic
imaging system might be configured so as to place a particular
celestial object within a target reticle of the imager and be
instructed to maintain the target star within the target area.
Thus, movement vectors can be derived from the direction and
magnitude of telescope motion required to maintain the target star
within the target reticle of an electronic imager.
[0122] Thus, the relative movement relationship of the celestial
coordinate system with respect to the telescope coordinate system
can be determined on the basis of a single star and the dynamic
movement direction and magnitude required by the telescope system
in order to track that star. It should be noted, that a relative
motion basis is determined using a single star sighting. A second,
separate, star might be acquired and used in the same manner in
order to obtain additional precision for overall alignment.
[0123] It should be noted that in the above-discussed drift
alignment methodology, there is no need to be concerned about a
time factor, the telescope's position or location on the earth's
surface, whether or not the telescope is level or any indicia
relating to either North or South. Drift alignment offers a
complete solution to the determination of a precise relationship
between the telescope coordinate system and the celestial
coordinate system by evaluating an object's actual track through
the night sky and determining its proper motion. However, the drift
alignment methodology is unable to provide the basis for local
sidereal time calculations and therefore, is unable to
automatically direct the telescope system to an externally
specified right ascension (RA) coordinate, unless additional data,
such as an object's identity, is supplied.
[0124] One additional sighting operation, in accordance with the
invention, is all that is necessary to derive local sidereal time
information from an initial alignment based on the above-discussed
drift alignment procedure. Once the relative movement of the
celestial coordinate system with respect to the telescope
coordinate system is determined, using the drift alignment
procedure, a user slews the telescope system, using the system's
hand box controller, to the celestial pole. Once pointed at the
pole, the orientation of the pole star clusters can be resolved,
using an electronic imager, and their rotational aspect can be
defined in a manner similar to reading the hands of a clock. Once
the rotational orientation of the pole star clusters is determined,
telescope system orientation is complete and the telescope system
now understands not only the relative movement of the celestial
coordinate system with respect to the telescope coordinate system,
but also its absolute rotational position with respect to an
observer. Thus, the telescope system can be aligned without the
user's having to enter any numeric data and without having to
engage in a time consuming leveling process.
[0125] A manual equivalent to this particular alignment procedure
might involve leveling the telescope, defining an altitude
reference point by pointing the telescope at the horizon, for
example, defining an azimuth reference point by pointing the
telescope North, for example, and then pointing the telescope at a
known star with known RA and Dec celestial coordinates. An
alternative manual equivalent might be to enter an observer's local
time, date and terrestrial location (latitude and longitude) and
subsequently have the telescope slew very close to an automatically
selected star for final synchronization. As can be seen, the manual
equivalent alignment procedures require either a fair knowledge of
the night sky (in order to point to a known star) or a fair
knowledge of time and position information (latitude and longitude
for example). Information of this type is not always easily
obtainable by first-time telescope system users. Accordingly, the
foregoing inventive alignment systems offer an interesting and
interactive approach to telescope alignment that only requires a
user to be able to follow the motion of the star through the
heavens and not concern themselves with remembering or entering
numeric data.
[0126] It should be understood, therefore that initialization,
orientation and alignment systems operative in the context of a
fully automated telescope system, are not limited to the particular
telescope configurations and embodiments described. Those having
skill in the art will immediately recognize that sequences of steps
may be re-arranged, inverted or otherwise modified without
departing from the scope and spirit of the invention. Accordingly,
the invention is to be defined only with regard to the appended
claims.
* * * * *